The present invention relates to a sound reproducing device, a reproduced sound adjustment method, an acoustic characteristic adjustment device, an acoustic characteristic adjustment method, and a computer program. More specifically, the present invention relates to a sound reproducing device and a reproduced sound adjustment method of performing adjustments of reproduced sound appropriate for individual users. Furthermore, the present invention relates to an acoustic characteristic adjustment device, an acoustic characteristic adjustment method, and a computer program, which make it possible to obtain reproduced sound having a good acoustic characteristic while an acoustic characteristic adjustment result received by user operation is taken into consideration.
In many cases, a sound reproducing device has an equalization function. An equalization function is used for: smoothing an auditory-perceptive acoustic characteristic by adjusting a frequency characteristic of reproduced sound; clarifying a sound image by emphasizing a specific frequency band, and the like. Furthermore, it is also used for obtaining a loudness effect of realizing a uniform auditory sensation by enhancing a low-tone range and a high-tone range at a small sound volume.
As an equalization function, a function of classifying a reproduced sound range into a plurality of sound ranges such as, for example, a low-tone range, a middle-low-tone range, a middle-tone range, a middle-high-tone range, and a high-tone range and arbitrarily setting the degrees of emphasis and reduction for each of the sound ranges and a function of selecting a frequency characteristic preset in accordance with a genre, a surrounding environment, user attribution such as age, and the like are practically used.
Meanwhile, a listening environment and the auditory sense of a user vary, and thus the frequency characteristic of a sound output from a sound reproducing device do not always coincide with an auditory-perceptive acoustic characteristic. For example, even when a sound reproducing device outputs a sound of a flat frequency characteristic, it sometimes happens that a specific sound range is heard in an emphasized manner or a specific sound range is heard in a weakened manner depending on a listening environment or the auditory sense of a user. Therefore, in recent years, reproduced sound has been equalized on the basis of an auditory-perceptive acoustic characteristic in order to enhance the functionality of an equalizer.
Auditory-perceptive acoustic characteristics have heretofore been adjusted by: alternately reproducing a comparative sound having a frequency band to be inspected and a reference sound having a frequency band wider than the above frequency band; and adjusting the sound volume of the comparative sound so that the comparative sound may be heard by a user as the same sound volume as the reference sound.
It is possible to obtain acoustically flat frequency characteristics for a user by: reproducing a sound in an emphasized manner because it sounds weak for a user in a frequency band where the sound volume of a comparative sound is increased so as to be higher than a prescribed level in adjustment; and reproducing a sound in a weakened manner because it sounds strong for a user in a frequency band where the sound volume of a comparative sound is decreased so as to be lower than a prescribed level in adjustment.
It is possible to enjoy audio reproduction more consistent with the preference or intention of a user by applying equalization desired by the user with reference to such an auditory-perceptive flat frequency characteristic (see Japanese Patent Application Laid-Open Publication No. H05 (1993)-206772 and Japanese Patent Application Laid-Open Publication No. H09 (1997)-027996, for example).
A method of reproducing a comparative sound and a reference sound alternately and adjusting the sound volume of the comparative sound so that the comparative sound may be heard as the same sound volume as the reference sound is, however, not an easy operation for a user and tends to be inaccurate since it relies on the memory of sound. In addition, a process of trial and error has to be repeated in order to compare the sound volumes and it is concerned that much time is required for reproduced sound adjustment operation.
Further, when a user adjusts an acoustic characteristic arbitrarily, it may sometimes happen that respective adjusted values in sound ranges vary extremely. An example is the case where, whereas the sound volumes of comparative sounds in a low-tone range, a middle-low-tone range, and a high-tone range are enhanced to the maximum scale value of +10, the sound volume of a comparative sound in a middle-high-tone range is reduced to the minimum scale value of −10 as shown in FIG. 1A.
If a reproduced sound is equalized on the basis of such an adjustment result, a reproduced sound having such an frequency characteristic as shown in FIG. 1B is obtained and unnatural music having an acoustic characteristic not intended by a sound source producer is undesirably provided to a user.
Furthermore, it is considered that such an extreme adjustment result is caused by inexperienced operation or faulty operation by a user in many cases. Consequently, if a sound having an acoustic characteristic obtained through the operation result by a user is directly reproduced, the user listens to music reproduced with an unanticipated frequency characteristic and the music becomes rather unpleasant to listen to because of the acoustic characteristic adjustment. On the other hand, if an adjustment result received by user operation is treated lightly, it means that the original purpose of equalization function is abandoned.